Battery operated electric vehicles are used in terrestrial, airborne, and marine surface and undersea applications. Typically, it is necessary to occasionally recharge a vehicle's batteries to enable continued operation. This is often done by connecting an electrical power supply to the electric vehicle via an electrical cable. In many environments, however, the need to make such an electrical connection can lead to several problems.
First, some electric vehicles operate in areas that are not easily accessed with an electric power cable. In some cases, the area may be quite remote, which would necessitate the use of a very long cable. Typically, a battery is charged with D.C. current. As a result, very long electric power cables can result in a large voltage drop, which makes the charging process energy inefficient and more time-consuming.
Second, some environments are not amenable to making and breaking an electrical connection. For example, some environments may have an atmosphere that is easily combustible or, alternatively, be underwater. Also, battery charging may be prohibited onboard some ships due to safety concerns. Further water intrusion in connectors and corrosion underwater can impact the reliability of such an electrical connection.
Third, it may be necessary to retrieve an underwater vehicle and allow it to dry before providing it an electrical connection to an external power supply. This can further reduce the efficiency of the recharging operation and reduce the overall operability of the electric vehicle.